Various apparatus are employed for arranging sheet material in a package suitable for use or sale in commerce. One such apparatus, useful for describing the teachings of the present invention, is a mailpiece inserter system employed in the fabrication of high volume mail communications, e.g., mass mailings. Such mailpiece inserter systems are typically used by organizations such as banks, insurance companies, and utility companies for producing a large volume of specific mail communications where the contents of each mailpiece are directed to a particular addressee. Also, other organizations, such as direct mailers, use mail inserters for producing mass mailings where the contents of each mail piece are substantially identical with respect to each addressee. Examples of inserter systems are the 8 series, 9 series, and APS™ inserter systems available from Pitney Bowes Inc. located in Stamford, Conn., USA.
In many respects, a typical inserter system resembles a manufacturing assembly line. Sheets and other raw materials (i.e., a web of paper stock, enclosures, and envelopes) enter the inserter system as inputs. Various modules or workstations in the inserter system work cooperatively to process the sheets until a finished mail piece is produced. For example, in a mailpiece inserter, an envelope is conveyed downstream to each processing module by a transport or conveyance including drive elements such as rollers or a series of belts. The processing modules may include, inter alia, (i) a web for feeding printed sheet material, i.e., material to be used as the content material for mailpiece creation, (ii) a module for cutting the printed sheet materiai to various lengths, (iii) a feed input assembly for accepting the printed sheet material from the cutting module, (iv) a folding module for folding mailpiece content material for subsequent insertion into the envelope, (v) a chassis module where sheet material and/or inserts, i.e., the content material, are combined to form a collation, (vi) an inserter module which opens an envelope for receipt of the content material, (vii) a moistening/sealing module for wetting the flap sealant to close the envelope, (viii) a weighing module for determining the weight of the mailpiece for postage, and (x) a metering module for printing the postage indicia based upon the weight and/or size of the envelope, i.e., applying evidence of postage on the mailpiece. While these are some of the more commonly used modules for mailpiece creation, it will be appreciated that the particular arrangement and/or need for specialty modules, are dependent upon the needs of the user/customer.
Inasmuch as a mailpiece inserter comprises a plurality of processing modules, it is oftentimes desirable to reduce the conveyance feed path, and, accordingly, the “foot-print” occupied by the inserter. That is, since the real-estate occupied by a mailpiece inserter translates into a “fixed expense” for an operator, it is desirable to reduce the space consumed by the inserter. As a result, savings can be achieved by reducing the length of the conveyance feed path.
Of the many challenges faced by designers of mailpiece inserters, one area which results in a requirement for greater space/length of the conveyance path is the transition between modules. That is, to accommodate sheets of variable length, or process certain mail run jobs, a threshold spacing must be maintained between modules to ensure that a downstream module does not prematurely begin processing/handling a sheet/collation before an upstream module has completed an operation. For example, it is common practice to lengthen the feed path, or include a buffer region between modules, to allow a larger sheet, e.g., 11×17 inch sheet, to be processed/handled by an upstream module without interference by a downstream module.
In the case of a print module, it will be appreciated that a blank sheet is fed past a printhead which prints from a leading to a trailing edge. As the sheet is fed and printed, the leading edge is conveyed downstream or “leads” as the sheet is printed along or near the trailing edge. No operation can be performed on the leading edge (which is now downstream of the printhead) while the trailing edge is being printed. As a consequence, the conveyance feed path will typically include the full length of a sheet before a downstream module can accept and begin another operation.
Another example includes the transition between a cutting module and a feed input assembly of a mailpiece inserter. In this example, the length of content material can vary from a short insert, i.e., approximately four and one-half inches (4½″), to a double-length sheet, i.e., approximately seventeen inches (17″). As a result, the feed path between the cutting module and the feed input assembly can vary by more than twelve inches (12″) or one foot (1′). Stated in yet other terms, the point of entry/ingestion of the leading edge of a long sheet can lengthen the feed path of the inserter as compared to the entry point required by a short insert, e.g., the location of a nip for ingesting the leading edge of the insert.
Finally, the initial set-up and anticipated processing of a sheet/collation can adversely impact the length of the conveyance feed path. For example, it is common practice to include a symbol/mark/scan code on one or more sheets of a collation to provide information concerning the processing of the collation. When accumulating a collation of sheets, a scanner disposed upstream of the accumulator, reads the symbol/mark/scan code so that the inserter may know when a collation begins or ends. That is, the mailpiece processor interprets the symbol/mark/scan code such that it may determine which sheet, of the stream of sheets being fed along a conveyance path, is the first sheet of the next collation.
As a result, information is obtained concerning when the Beginning Of the next Collation (BOC) begins and/or when the end of the current collation ends. Depending upon the location of this symbol/mark/scan code, the length of the conveyance feed path (between an upstream singulating module, i.e., a module which singulates/feeds sheets, and a downstream accumulator), must accommodate the longest sheet anticipated to be processed. If, for example, the symbol/mark/scan code is located along a trailing edge of a sheet to be processed, then the length of the conveyance path must be at least as long as the distance between the leading edge of the sheet and the BOC plus a threshold pitch distance (i.e., the distance between the trailing edge of one sheet and the leading edge of the subsequent sheet as determined by the throughput requirements/speed of the mailpiece inserter).
In each of the above examples, it will be appreciated that conveyance systems of the prior art are constrained by a requirement to accommodate processing of the largest sheet, whether dictated by the length dimension of the sheet, or the location/position of a symbol/mark/scan code on the face of the sheet. As a result, the overall foot-print/size of the sheet handling system, e.g., a mailpiece inserter, is increased by the limitation to maintain a minimum spacing, or threshold distance, between modules.
Yet another challenge for designers of mailpiece creation systems relates to the audible noise levels produced by the sheet feed mechanisms upstream of the accumulator assembly. To the extent that such sheet feed apparatus employ vacuum feed devices, the audible noise levels produced by rotating vacuum rollers can create significant discomfort for operators of the mailpiece creation system. Generally, such devices can have the fluid flow characteristics and, respective, sound levels of a conventional rotating siren/horn.
A need, therefore, exists for an apparatus for reliably singulating sheet material sheets without the operator discomfort and other limitations of prior art sheet handling systems.